Intention

Thinking back on optical illusions I've seen in the past, I can only remember one that has really stood out to me. When I visited the Museum of the Moving Image in the neighborhood I grew up in, I saw the piece Feral Fount, and was amazed by how simply adding a blinking light could drastically change how I viewed the piece. My first impressions were something along the lines of being unimpressed and waiting for something to happen, but when the blinking light turned on, I couldn't stop staring. I wanted to know more about how it worked and why one simple change could make such a difference.

Perceptual Illusion

Feral Fount is a stroboscopic zoetrope created by Gregory Barsamian. It features 97 slightly different sculptures that are placed on a rotating armature. When viewed normally, there is nothing out of the ordinary to be seen, but when viewed with a strobe light that flashes 13 times per second, it causes the optical illusion “persistence of vision” and the sculptures seem to blend together to form an animation of a drop of water morphing into a bomb, then a paper airplane, and finally a dish.

The frame rate of 13 times per second is within the range at which the human eye can perceive motion. The flashes of darkness created by the strobe light prevent the human eye from seeing blur as should normally be seen. Persistence of vision is the effect in which images remain on the retina even when there is no such image. Images can remain for about 1/30th of a second, which is why the effect works.

Examples in the world

A zoetrope was originally a toy created for amusement and to make pictures “move”. One such example is the spinning drum, in which images are inside the inner wall of the drum, and there are slits along the walls of the drum so that when the drum is spun, it creates an effect that makes it seem as if the images are animated. The slits prevent the viewer from simply seeing a blur.

Another real life example that uses persistence of vision is, perhaps not surprisingly, another toy called a thaumatrope. This toy was created using a small disk with different images on each side. Strings were attached to the disk so the disk could be spun quickly, and the images on the sides of the disk would blend together to form one image. The faster the disk was spun, the more the images blended together.

Examples in Media/Art

The Masstransiscope was created in the NYC subway tunnels. Hand-painted panels were placed into panels in the wall such that people on passing subway trains would see a moving image instead of individual images.

Another example is an effect known in the Captain Underpants series. Each book had several “Flip-o-rama” sections where you held one page down and quickly flipped the next page back and forth to make it seem like the images on the two pages created an animation.

Flipbook animations were created solely to leverage this optical illusion. Multiple images that drawn on several pieces of paper and flipped through rapidly to make it seem as the separate images are combining to form an animation.

Reflection

Before seeing Feral Fount, I had known about this visual effect before, but didn’t know there was a name for it and the reasoning behind it. I also did not know that Feral Fount used the exact same effect, because I didn’t know how the blinking light could make the images seem to blend together. Over the course of the project, I found it fascinating that some of the examples I found were quite childish in nature, relating to toys and children’s books. However, I think this optical illusion can draw anyone in no matter what their age is. In my own digital media, I can use persistence of vision to create visual animations by simply drawing several images that slightly differ from each other and combine them together.